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The scanner i have says code 1 of 2, and it tells me i have p0420 both times.
What do you think this means? Maybe both o2 sensors are bad, or getting bad readings?

I hope its just the scanner being weird and i just have one CEL problem. I know i have a bad cat which would give the secondary o2 sensor a bad reading. If the primary o2 is bad, then i got problems, lol. Maybe a head gasket problem, if it burns oil, and the oil cakes up the sensor. Idk maybe im just being a little parnoid, but let me know what you think.

One is probably the code when it was pending, i.e. the ECU was waiting to see if it registered another 'event' before throwing the CEL, the other is the confirmation of that 2nd event i.e. when your CEL came on.

One is probably the code when it was pending, i.e. the ECU was waiting to see if it registered another 'event' before throwing the CEL, the other is the confirmation of that 2nd event i.e. when your CEL came on.

Whether your cat is gone or it's a sensor issue I couldn't say.

Ok, that makes sense.
and I know for a fact i have a bad cat. Costs $800 and doing that sometime next month. Just hope thats all.

Sorry for barging into your thread, guys, but I thought because it's only a day old I won't be dredging up old threads, and it's directly relevant (I think) to your post. I'm totally new, and it won't let me post a thread yet, so I'm begging for someone to give me a boost sort of thing. I'm just trying to get some response from guys who sound like they know a heck of a lot more about it than me.

I've been trying to do the right thing and search as much as I can through other threads about this issue, but I'm coming up with conflicting information, and seeing as how you guys are discussing this tonight I thought you might not mind if I tagged along sort of.

I'm throwing p0420 also, on an '07 totally stock rs wagon which has been maintained absolutely mint all the way up to 143,000 which is where it is now, and that leads me to the 1st totally noob question that I hope sort of fits in here: Is expert maintenance and proper fuel system oversight going to prolong the life of the cat or the sensors, or do they last a predictable amount of time or miles, or do they just fluke out and fail whenever due to manufacturing errors and the like?

I guess my point is I know the previous owner maintained this car to the hilt, and spared no expense eliminating any problems immediately, does this mean that I have better chances of the cat being good for longer??

Again lads, sorry for the hijack, but since I have no posting privileges yet I thought this thread sounded like a maybe-not-get-booted way to post my questions.

Ok, that makes sense.
[A]nd I know for a fact i have a bad cat. Costs $800 and doing that sometime next month. Just hope that[']s all.

$800?! I assume that's for the OEM part? There are much, much cheaper options on www.rockauto.com. There's not a snowball's chance in hell I'd pay $800 for a cat pipe.

I assume you've already replaced the O2 sensors? When you say you know you have a bad cat, how is that? Is the catalyst bed broken up inside (and you can hear it rattling around)?

Quote:

Originally Posted by RolySaul

I guess my point is I know the previous owner maintained this car to the hilt, and spared no expense eliminating any problems immediately, does this mean that I have better chances of the cat being good for longer?

$800 seems pretty high considering the cost of the materials, but I always do the work on my cars so my view of what things should cost is skewed. I think you should give some thought to upgrading to a set of stainless headers and cat section of your choice. You have to do more leg work, but you could save some of your hard earned money.